1. Field of the Invention
The present invention relates to a printing apparatus which discharges an ink toward a printing medium and conducts printing operation.
2. Related Background Art
In a conventional liquid jet (ink jet) system printing apparatus, for the purpose of removing an ink which cannot be discharged with a high precision because the ink viscosity is increased due to dusts mixed into nozzles of a liquid jet head or dryness, or another kind of ink mixed into a flow path through which the ink is supplied to the interior of the nozzles, etc., there are provided suction recovery means for forcibly discharging the ink or a foreign material from the nozzles of the liquid jet head, and preliminary discharge means for discharging or exhausting the ink to a preliminary discharge acceptor port disposed on a location other than the printing medium by a given number of times before the printing operation or during the printing operation.
However, if the scanning direction of the liquid jet head substantially coincides with the longitudinal direction of a nozzle array formed in the liquid jet head, a cap made of rubber or the like which constitutes a part of the suction recovery means and covers the nozzle formation surface of the liquid jet head and the preliminary discharge acceptor port for receiving the ink discharged by the preliminary discharge operation are arranged longitudinally vertically. As a result, a large space is required within the printing apparatus, and the downsizing of the printing apparatus is obstructed.
As a method of preventing the above drawback, there has been proposed a so-called in-cap preliminary discharge which preliminarily discharges the ink within the cap. However, in this event, there is a case in which, for example, an ink mist discharged from the liquid jet head at the same time of the main ink droplet during the preliminary discharge operation, a splashed mist occurring when the main droplet is grounded in the interior of the cap, etc., are attached onto a close contact surface of the liquid jet head with the nozzle surface and deposited and then so dried as to be solidified. When the ink solidified portion occurs on the close contact surface of the cap, the nozzle surface of the liquid jet head cannot be sealed with the cap, as a result of which a satisfactory performance may not be obtained. In particular, in the case where a pigment ink which is difficult to again dissolve if the ink is dried and fixed once is employed, even if a fresh ink which is newly preliminarily discharged is exposed on the ink fixed on the cap, the above problem could not be solved. In addition, in the printing apparatus having the possibility that a large amount of dusts or foreign material such as paper powders occurs inside, the deposited ink and foreign material are repeatedly attached onto the cap, and there is a fear that the performance is further deteriorated.
The present invention has been made in order to solve the above problems, and therefore an object of the present invention is to provide a printing apparatus which preliminarily discharges the ink to the exterior of the cap and is downsized.
In order to achieve the above object, according to one aspect of the present invention, there is provided a printing apparatus on which a liquid jet head having a nozzle array made up of a plurality of nozzles is mounted to conduct printing operation, the printing apparatus comprising: a preliminary discharge acceptor port which receives a discharge liquid not used for the printing operation from the nozzles of the liquid jet head; wherein a length of the preliminary discharge acceptor port along the arranging direction of the nozzle array is shorter than the length of the liquid jet head along the arranging direction of the nozzle array.
The liquid jet head is driven by driving control means disposed in the printing apparatus, and the drive control means divides the nozzle array of the liquid jet head into a plurality of blocks. It is preferable that the ink discharge operation is sequentially conducted with respect to the preliminary discharge acceptor port for each of the divided nozzle blocks under control. In this case, the divided nozzle block is shorter than the length of the preliminary discharge acceptor port along the nozzle array arranging direction.
With the above structure, without making the printing apparatus so large, the preliminary discharge operation can be conducted on the preliminary discharge acceptor port except for the cap.
Sucking means which can generate a negative pressure may be connected to the preliminary discharge acceptor port so that the ink reserved within the preliminary discharge acceptor port is removable by the sucking means. In this case, another member is prevented from being stained by the ink reserved within the preliminary discharge acceptor port. The sucking means may be common to negative pressure generating means for sucking and recovering the liquid jet head.
Also, it is preferable that an absorber is disposed in the preliminary discharge acceptor port.
The preliminary discharge means may sequentially discharge the ink from the liquid jet head for each of the nozzle blocks while the liquid jet head is continuously moving by liquid jet head moving means. In this case, a period of time required for the preliminary discharge operation is shortened.
Also, the preliminary discharge means may discharge the ink from the liquid jet head in a state where the liquid jet head is sequentially moved for each of the nozzle blocks by the liquid jet head moving means, and a given nozzle block reaches the upper portion of the preliminary jet acceptor port and stops moving.
The preliminary discharge acceptor port may be provided in a recovery system unit.
Also, according to another aspect of the present invention, there is provided a printing apparatus, comprising: a liquid jet head having a nozzle array made up of a plurality of nozzles; liquid jet head moving means for retaining the liquid jet head and scanning substantially in parallel with the nozzle array direction; preliminary discharge means for discharging the ink to a place other than the printing medium; preliminary discharge acceptor port for receiving the ink discharged by the preliminary discharge means; a cap for capping the nozzle surface of the liquid jet head; and a pump connected to the preliminary discharge acceptor port and the cap.
In this structure, it is preferable that there is further provided a valve which changes between the connection of the pump and the cap and the connection of the pump and the preliminary discharge acceptor port.
Further, another object of the present invention is to provide a preliminary discharge acceptor mechanism which receives a discharge liquid not used for the printing operation from the nozzles of a liquid jet head in a printing apparatus on which a liquid jet head having a nozzle array made up of a plurality of nozzles is mounted to conduct printing operation; wherein a length of the preliminary discharge acceptor port along the arranging direction of the nozzle array is shorter than the length of the liquid jet head along the arranging direction of the nozzle array.
Also, it is preferable to provide sucking means which can generate a negative pressure to the preliminary discharge acceptor mechanism so that the ink reserved within the preliminary discharge acceptor mechanism is removable by the sucking means.
Also, it is preferable that an absorber is disposed in the preliminary discharge acceptor mechanism.
Further, it is preferable that the preliminary discharge acceptor mechanism is disposed in the recovery system unit.
Still further, it is preferable that there is further provided a valve which changes between the connection of the sucking means and the cap of the recovery system unit and the connection of the sucking means and the preliminary discharge acceptor mechanism.